Metal etching stylus



April 13, 1943. R. B. ANNIS METAL ETCHING STYLUS Filed Dec. 13, 1941 Patented Apr. 13, 1943 UNITED STATES PATENT OFFICE 2,316,388 METAL ETc-HING STYLUS Robert B; Anne, inaiailalioiis', I nd. Application December 13, 1941, Serial No. 422,855

6 Claims.

This invention relates to means for electrically etching directly upon metal. An application of the invention is found in applying identifying characters or parts numbers to individual tools,- such as milling cutters, and to individual partsof machine assemblies. Such marking or numbering of parts by the electric etching device is of particular advantage where the tools or parts are made of hardened steel, a situation wherein it is difficult to employ other means of marking.

The etching process is carried out in general by guiding a metallic electrode to trace the pattern or character to be etched directly on the member, which member is made the terminal of one side of a circuit, the electrode being the terminal of the other.

A primary object of the invention is to provide means for holding and guiding the electrode over the part to be etched in a manner whereby the electrode will be held substantially perpendicular to the etched surface while the electrode guiding means may be held in the operators hand in much the same manner as a pencil or pen during a writing operation.

A still further important object of the invention is to provide a structure whereby the current carrying conductor does not pass through the member held in the operators hand. An important advantage of the invention is that the electrode may be guided during the etching operation in substantially the same manner as direct writing upon the surface, all without'inconve'nience or annoyance to the operator from heat arising in the electrode. During the etching process, particularly if the process is carried on over any considerable period of time, the'etching electrode will become heated to that degree whereby contact of the electrode with the operators hand would cause severe burning, a situation which is eliminated by use of the present invention.

These and many other objects and advantages of the invention will become apparent to those versed in the art in the following description of one particular form of the invention as illustrated in the accompanying drawing; in which Fig. l is a view in a perspective ofa device embodying the invention;

Fig. 2, a view in side elevation on an enlarged scale of the stylus of the etcher;

Fig. 3, a view in top plan;

Fig. 4, a view in front elevation; and v s Fig. 5, view in section on the line --5in" Fig. 4.

Like characters of reference indicate like parts throughout the several views in the drawing.

Referring first to Fig. l, the box It) is eniployed to contain the usual current regulating' transformer (not shown), the details of which do not enter into the present invention. In any event, one terminal of the secondary winding of the transformer is connected directly to the me tallic plate H which forms the top closure of the box 0. The other terminal leads to an outlet in the side of the box into which the terminal l2 fixed on the cord I3 may be inserted. I'he voltage between the plate I I and the conductor in the cord I3 is quite low, in fact so low that the operator may rest his hand directly on the plate I l to bridge across with the cable conductor without any sensation of current passage through his hand.

The cable l3 carries an attaching terminal on its end removed from the terminal I2.

A bracket I5 is formed to have a head It through which is transversely inserted a headless bolt H, the bolt I! being free to slide through a bore provided in the head It. The head lfiis vertically bored off center in relation to the transverse axis of the bolt [1 therethrough, Fig. 5, in such manner that an electrode I8 may be inserted and passed vertically through the head l6, substantially half of horizontal diametrical plane through the head I6, passing through the bolt [1 and the other half therebehind through the head Hi. In other words, the bolt ll isprovided with a transverse slot thereacross, throughwhich' slot the electrode l8 passes.

This slot across the bolt l1 is located in that position whereby, when the electrode l8'is inserted through the head l6a'nd the bolt ll, one end of the bolt H is flush with the side face of the head l6 and the other end of the bolt l1 extends outwardly beyond the opposite face of the head to present a screw-threaded end over which is placed the terminal l4 and a nut 19' screw-threadedly engaging that end of the bolt" ll. By tightening thebolt ll bore in the head I 6 but such tendency is overcome by reason of-the" slotted portion of the bolt I l engaging the electrode l8; whereupontheelectrode I8 is firmly seated in the head I 6 by tightening that nut l 9, at the same time firmly pressing the terminal i4 against the head. Theelecup the nut IS! on the bolt IT;

trode l8 may accordingly; be adjusted vertically upwardly and downwardly through the head- It the electrode l8, at the.

is tended to be pulled through the to have the desired length of electrode extending below the head.

The head I6 is mounted in offset relation to a shank 20 of the bracket so that this shank may extend along in substantial parallel alignment with but be spaced apart from that part of the electrode i8 which extends below the bracket head it. The lower end of the shank is turned outwardly and downwardly to have attached thereto a pencil-like member 2|, means of the attachment being herein shown as a screw 22 passed through the end of the shank 23 and screw-threadedly engaging axially within the lower end of the member 2i. The axis of this member 2| is in a common plane with the axis of the electrode Hi. This member 2i is made out of any suitable insulating material, preferably for both heat and electrical insulation.

In the present form of the invention a fin 23 is provided to extend rearwardly from the head l5 and continue downwardly to blend into'the shank 25. This fin 23 serves to radiate heat from the head 16 which may be transmitted thereto by the electrode 18. electrode I8 is pointed sharply and the electrode is adjusted to bring the point on ie line of the axis of the member 25. By so locating the point of the electrode l8, the member 2! may be grasped the same as one would a pen holder or pencil, and place the point of the electrode 18 on the object 24, Fig. 1, to be etched, whereupon the operator may direct the electrode point with exactly the same mode of muscular control as he would a pencil or pen. In so doing, it is to be noted that the cable 13 carrying the current to the electrode 18 does not pass through that handle member 2| but is carried directly to the head 5 for connection with the electrode l8. Also it is to be noted that by reason of the angular disposition of the member 21, the electrode l8 may be held in its best operating position, which position is that where the axis of the electrode is perpendicular to the face of the object 24.

a By reason of the shank 23 having a greater width, Fig. 4, than that of the electrode 13, this shank 2!! serves very efliciently as a heat shield for the operators forefinger which normally would lie upon the upper side of the member 2 I, Fig. 1. Even though the shank 28 should become warm, the handle member 2| being of insulating material remains relatively cool even under continued etching. When the point of the electrode It becomes dull, the electrode 18 may be removed quickly from the head l6 by loosening the nut l9; re-sharpened; and again fixed in position by insertion through the head and tightening up of the nut l9.

Preferably the bracket I5 is made out of a material that is less heat-conductive than that of the electrode 18. Normally the electrode [8 would be made out of copper or a copper alloy, the point in particular being of copper alloy or even tungsten. The bracket 15 in one particular instance is made out or" malleable iron which inherently is a poorer heat conductor than copper. Thus it is to be seen that the combination of the stylus embodies three essential interconnecting members, the electrode IS, the bracket (5, and the handle or holder 2!, each having less conductivity than the other in the order named. The cable I3 is preferably reenforced adjacent the terminal M by any suitable covering means, such as a length of tubing In practice, the

made out of one of the synthetic rubbers which is oil resistant.

While I have herein shown and described my invention in the one particular form, it is obvious that structural variations may be employed without departing from the spirit of the invention and I therefore do not desire to be limited to that precise form beyond the limitations as may be imposed by the following claims.

I claim:

1. For an electric etching device, a stylus comprising a bracket having a shank and a head at the upper end of and in oifset relation to the shank, an electrode, means for adjustably carrying the electrode from said head, a pencillike member carried by the lower end of said shank at an acute angle to said electrode, the axis of said electrode and said member being in a common plane, said electrode being in spaced, substantially parallel alignment with said shank,

and said shank being wider than said electrode to serve as a shield thereacross.

2. For an electric etching device, a stylus comprising a bracket having a shank and a. head at the upper end of and in ofiset relation to the shank, an electrode, means for adjustably carrying the electrode from said head, a pencil-like member carried by the lower end of said shank at an acute angle to said electrode, the axis of said electrode and said member being in a common plane, said bracket being of a heat conductivity relatively less than that of said electrode, and said bracket further having a greater width than said electrode to serve as a shield between the electrode and said member.

3. For an electric etching device, a stylus comprising a bracket having a shank and a head at the upper end of and in offset relation to the shank, an electrode, means for adjustably carrying the electrode from said head, a pencil-like member carried by the lower end of said shank at an acute angle to said electrode, the axis of said electrode and said member being in a common plane, and a heat radiating fin projecting toward said member from said head and around from the upper end of said shank.

4. For an electric etching device, a stylus comprising a bracket having a shank and a head at the upper end of and in ofiset relation to the shank, an electrode, means for adjustably carrying the electrode from said head, a pencil-like member carried by the lower end of said shank at an acute angle to said electrode, the axis of said electrode and said member being in a common plane, said means consisting of a vertical bore through said head, a transverse bore thro gh the head communicating with the vertical bore, a bolt slidingly carried in the transverse bore and having a transverse notch thereacross, said electrode being positioned in said head vertical bore to be engaged by said notch, and means for pulling the bolt axially to grip the electrode accordingly in the head.

5. For an electric etching device, a stylus comprising a bracket having a shank and a head at the upper end of and in offset relation to the shank, an electrode, means for adjustably carrying the electrode from said head, a pencil-like member carried by the lower end of said shank at an acute angle to said electrode, the axis of said electrode and said member being in a common plane, said means consisting of a vertical bore through said head, a transverse bore through the head communicating with the vertical bore, a bolt slidingly carried in the transverse bore and having a transverse notch thereacross, said electrode being positioned in said head vertical bore to be engaged by said notch, and means for pulling the bolt axially to grip the electrode accordingly in the head, and a conductor secured to said head by said bolt pulling means.

6. In an electric etching device, a stylus comprising a hand grip in the nature of a pencil made of heat and electrical insulating material; an upturned bracket extending from the lower end of the grip to be in a substantially vertically disposed position when the grip is supported in a normal writing position; a head on the upper end of the bracket; an electrode adjustably retained as to extended length by said head to maintain the electrode in closely spaced relation to said bracket on the side thereof removed from said grip; said bracket being wider than said electrode; and means for securing an electrical conductor to said bracket head; whereby said grip is removed from immediate heat transfer from both said conductor and said electrode and the lower point of the electrode guided as though it were the point of said grip.

ROBERT B. ANNIS. 

